Troops were collected, but whilst conducting a campaign against the Romans, Otto died at Paterno near Viterbo on the 23rd of January 1002, and was buried in the cathedral at Aix-la-Chapelle.
The cardinal therefore obtained a bull from Pope Paul II., permitting him to recall his original donation, and in a letter dated from the baths of Viterbo, May 13th, 1468, he made over his library to the republic. The principal treasures of the collection, including splendid Byzantine book-covers, the priceless codices of Homer, the Grimani Breviary, an early Dante, &c., are exhibited under cases in the Sala Bessarione in the Zecca or mint where the library has been installed.
He and his elder brother Giuseppe (known as Cardinal Pecci) received their earliest education from the Jesuits at Viterbo, and completed their education in Rome.
From the 14th century to the middle of the 16th, Ubertin of Casale (in his Arbor Vitae crucifixae), Bartholomew of Pisa (author of the Liber Conformitatum), the Calabrian hermit Telesphorus, John of La Rochetaillade, Seraphin of Fermo, Johannes Annius of Viterbo, Coelius Pannonius, and a host of other writers, repeated or complicated ad infinitum the exegesis of Abbot Joachim.
On the formation of the kingdom of Italy in 1860 they were reduced to the Comarca of Rome, the legation of Velletri, and the three delegations of Viterbo, Civita Vecchia and Frosinone; and in 1870 they disappeared from the political map of Europe.